It seems when you level up your souvereign, the sight range decreses the first few levels. Here are some screenshots:
And another one...
Edit: Seems I can't get these screenshots to work... So, these were supposed to be two screen-shots from my souvereign when he's leveling up. At the screen with the overview of the stat changes, you'll see to sight range go down which to me looks like a bug.
Edit 213 or something... Seems I finally got them to work 
